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Underground power lines

To make the electrical connection of the EDF network to your home, to bring a line to an adjoining building or to light your garden, you will have to create a power line that will be better buried. To do this, it is essential to take a number of specific precautions due to the natural humidity of the environment. The tightness of electrical conduits and appliances is here a mandatory rule with standards that must be known before performing the work. Manufacturers therefore offer equipment specially designed for this purpose and meeting these standards.

Necessary material

  • Cordeau
  • Spade
  • pickaxe
  • Mesureing tape
  • Lady
  • grilling
  • ICTA-3422 or ICA 3321 sealed electrical conduit
  • Multicore cables U 1000 R2V
  • Spraypaint
  • Plaster
  • Sand

Underground power lines: ducts

1. Trace the location of the trenches first with a chalk line, dusting them with a little plaster to mark their boundaries with white lines. In the absence of plaster, plant small stakes in the soil, along the wire. When trenches are traced, take into account the obvious fact that the shortest path between two points is the straight line: this allows the use of a minimum of ducts and conductors. It is always advisable to draw on the paper a preliminary plan of the general assembly; keep it to remember the exact location of the ducts.

Underground power lines: electrical

2. Using a spade and a pickaxe, dig the trenches along the path. Avoid digging these trenches in wet areas where water stagnates for a long time. Instead, choose dry, well-drained soils (sandy and stony).

Underground power lines: lines

3. The depth of the trench should not be less than 70 cm: check it in different places. The width depends on the number of ducts that you want to install (move the electrical ducts away from each other by about 10 cm for safety reasons), and on the other hand the width of the protective mesh (30 cm in general).

Underground power lines: power

4. Place a bed of sand about 10 cm thick at the bottom of the trench; trim it with the spade. This layer is intended to allow the flow of rainwater, to prevent the ducts from staying in a stagnant humidity. This bed is useless in well-drained terrain, rich in sand and gravel.

Underground power lines: power

5. Unwind the electrical ducts (ducts) at the bottom of the trench. Choose electrical conduits made of insulating, waterproof and bendable plastic. Ringed flexible ducts (ref ICTA-3422 or ICA-3321) are best suited for buried installation. The flexibility of these ducts leads to digging in a curve and not at a right angle, when the trench must turn.

Underground power lines: electrical

6. You can then pull the electrical conductor (type U 1000 R2V) into the sheath using the metal needle (metal wire). It is often easier to pass the conductor (which must not have a fitting) in its sheath before putting the assembly in the trench.

Underground power lines: lines

7. Using the spade or shovel, cover the ducts in place with a layer of sand (10 cm) so that they are completely embedded in this bed. When the trenches are used for the passage of pipes of different types (gas, water, etc.), it is necessary to observe a spacing of at least 20cm between these and the electrical conduits.

Underground power lines: ducts

8. If you do not have the red plastic wire mesh warning sign, paint in red, with a spray of paint, a 30 to 40 cm wide wire mesh, the length of which is equal to the trench. Roll this tape to make it easier to paint and use a moisture-proof paint. When one digs, the presence of the red protective mesh allows to detect, without risk of confusion, the presence of the electric conduits.

Underground power lines: power

9. After drying the paint, unroll the mesh on the bottom of the trench. The grid, placed about 50 cm from the surface, makes it possible to work the soil above the pipes for the cultivation of plants with small roots, vegetables for example. It is, of course, impossible to plant shrub species, whose roots sink too deeply. Whenever possible, run ducts under uncultivated areas of the garden (eg driveways), where they are not likely to be damaged by cultivation work (decide on the location of the garden, trees, etc.).., according to the routing of the cables).

Underground power lines: power

10. Finish backfilling the trenches by tamping the ground with a lady. Allow a long enough duct length to connect to the devices. Remember that all lighting fixtures, switches and junction boxes must be watertight, glanded and grounded.

Underground power lines: ducts

11. The line which you will have thus buried, will be able to come out by a junction box to feed either an annex building, or to provide outside a possibility of plugs (waterproof) to connect devices dedicated to the garden: electric mower, lighting, pond pump, etc...

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